Hybrid gas turbine engine starter-generator

Abstract

A rotating electrical machine, such as an aircraft starter-generator, that may be operated in either a DC motor mode or an AC generator mode. The machine includes a conventionally wound main stator that is selectively configurable as a multi-pole AC stator and a multi-pole DC stator. The machine also includes rotor windings that are configured to be selectively coupled to either an exciter or a plurality of commutator segments, and DC brushes that are selectively moveable into, and out of, electrical contact with the commutator segments, to thereby electrically couple and decouple a DC power source to and from, respectively, the rotor windings.

Description

TECHNICAL FIELD[0001]The present invention relates to rotating electrical machines such as starter-generators for gas turbine engines and, more particularly, to a hybrid starter-generator that is selectively convertible between operation as an AC generator and a DC motor.BACKGROUND[0002]An aircraft may include various types of rotating electrical machines such as, for example, generators, motors, and motor / generators. Motor / generators are used as starter-generators in some aircraft, since this type of rotating electrical machine may be operated in both a motor mode and a generator mode. A starter-generator may be used to start the engines or auxiliary power unit (APU) of an aircraft when operating as a motor, and to supply electrical power to the aircraft power distribution system when operating as a generator. Thus, when operating as a motor, a starter-generator may be designed to supply mechanical output torque sufficient to start the engines.[0003]One particular type of aircraft ...

AI Technical Summary

Benefits of technology

[0009]The present invention provides a starter-generator that does not incorporate relatively complex power conversion and frequency control circuits, which reduces the weight and cost as compared to some current starter-generators, that may increase the wear life of the DC brushes, which reduces the need for cleaning and maintenance, and that does not rely on a specially wound stator.

Problems solved by technology

The above-described starter-generator may include relatively complex and heavy power electronics circuits in the control device.

For example, some control devices may include inverters, for converting DC to AC power, rectifiers, for converting AC power to DC power, and potentially complex voltage and frequency control circuits.

Although brush-type DC machines may alleviate the need for some of these complex and heavy electronic circuits, these also suffer certain drawbacks.

For example, the brushes tend to wear fairly quickly, reducing machine reliability, and increasing the need for periodic maintenance and cleaning.

Although this prior approach addresses the noted drawbacks, it too presents certain drawbacks.

In particular, the specially wound main stator, which includes additional segments and windings, is more complex than a conventionally wound stator, which can increase overall costs, and adversely affects power quality when operating in the generator mode.

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